This study was conducted in two typical rural regions in the middle
region of the Wei River catchment (107°04′–107°59′E and 34°31′–
34°74′N) (Fig. 1). One region (S1) is located in Qianyang County along
the Qian River, a branch of the Wei River. S1 has an area of 2290 ha
and has approximately 50,000 inhabitants scattered in hilly regions
where arable land is terraced and fruit trees are commonly grown.
Wheat and maize are also cultivated and irrigated on the limited flat
land. The steep slopes of the land and the concentrated rainfall (June
to September) have led to serious losses of soil and nutrients and to
the degradation of the land. Most of the younger farmers (b40 years
of age) also work outside this area due to the difficulty in procuring an
adequate income. The other selected region (S2) is located at the junction
of the Chencang and Qishan County on the north shore of the Wei
River. S2 has an area of 1560 ha and approximately 45,000 inhabitants.
The farmland is flat, and the irrigation systemiswell developed. S2 has a
convenient transportation system and good farming conditions. Mushrooms
and vegetables are grown in small-scale greenhouses, and traditional
crops such as wheat and maize are intensively cultivated. Both
study sites are far fromlarge urban areas and are thus not strictly supervised
by authorities. The practices of agrochemical use are thus determined
by the level of knowledge of the local farmers.